Process of forming compound metal bodies



`I uly 29, 1930. F. EHRMANN 1,771,620

Pnocsss op romana coMPouNn METAL Bcmms I Filed Feb. 11, 1927 Fig. 1

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W; llll" INIIlu Patented July 29,1930

UNITED STATES PATENT OFFICE FRIEDRICH EHBMANN, OF EEUERBACH, STUTTGART, GERMANY, ASSIGNOB TO ROBERT BOSCH AKTIENGESELLSCHAFT, OF STUTTGART, GERMANY PROCESS 0F FORMING COMPOUND METAL BODIES Application illed February 11, 1927, Serial No. 167,564, and in Germany April 19, 1926.

' This invention relates generally to processes of forming compound metal bodies and it relates more particularlyto processes of applying-an outer orinner jacket to pressed metal rods, tubes, etc. For this purpose it has been proposed to place a rod made of the core metal, inserted into a completely formed tube made of the covering metal, into a cold press and to draw both together through the mouthpiece of the press. In doing so the covering tube is pressed firmly upon the core rod and moreover both are constricted and stretched proportionately in accordance with the opening in the mouthpiece of the press.

This known process isnevertheless diiiicult and expensive. That is, the core rod and the covering tube must .be passed one or more times through other accurately working presses in order that they may be suited for the known process. This process 1s suited, moreover, only for relatively soft easily workable metals.

According to the present process, which is an essentially simpler and cheaper process than that just described and which is adapted to most metals, the metal of the core and the metal of the jacket, roughly preformed in raw state, are superposed in proper order in the receiver of the press. lf these raw pre-formed blocks are exposed to the pressure of the press the jacket metal is carried along upon the rod of the core metal as an entirely uniform firmly clinging coating.

In the drawings is shown an example of the press intended for carrying out the process, represented in working position.

Fig. 1 shows in section a press for applyin an outer coating.

Fig. 2 also in section, shows a press for the inner coating of tubes.

In each case there is a cylinder a, which is intended for the reception of the metal block to be pressed out, the cylinder on one end being closed off by', a plate b having a thick wall.` In the plate b is a hardened matrixor die c, the hole d of which corresponds to the cross section which thel rod to be pressed is to have.' In theA other end of the cylinder a is a plunger f which under sufficient pressure forces the metal charge of the cylinder a out` through the mouthpiece c in the form of a rod. In the example shown in Fig. l a block A of metal for the core of the rod to be pressed is placed inthe cylinder a in accordance with the process. The block is conically pointed at the end turned towards the mouthpiece c and thereby leaves space for the conical ring B of the metal which is to form the coating for the rod.

Vith sutlicient pressure of the plunger f the block A placed in position and at press temperature is forced through the mouthpiece and emerges from it as a rod. At the same time a certain portion of the metal ring B is carried along by the core metal flowing towards the mouthpiece and this remains clinging to the rod of the metal core originating in A as an entirely uniform closely adhering coating'. The coating clings as lirmly as though it were welded to the core metal and it is completely uniform over sov the Whole length of the rod up to 30 m. and t more.

As can be seen the blocks do not need to fit each other very closely, as in the known processes, for they are not placed one with- 1n the other but rather are placed one behind the other inplayers. Those pieces which as female and male cones are placed one within the other need to tit each other only roughlyl and with much less exactitude than is necessary for very simple, cheap pieces hammered on an anvil.

In the example shown in Fig. 2 the press plunger f is longitudinally bored through and in known manner receives the fixed mandrel g which is necessary for making tubes. In this case the block C of the metal forming the tube has a conical depression on the end remote from the mouthpiece c. Into this projects the conically pointed end of anl annulus D made of the metal for the inner covering.

The block as a tube between the mandrel g and the wall of the mouthpiece c. In this operation the annular block D is carried along and brought out by the tube produced, in the form of a tightly clinging inner coating.

C in the pressing is forced out g5 vpointed-end block The thickness of the coating can be regui lated by suitable changes in thesize andlshape of the rings B and D. For` example, 1n the process according to Fig. 1 the flat rings of small cross section give thin coverings, thick rings with large cross sectionv of sharp conical form on the contrary give thickwalled coverings.

The process is not limited to round cross sections or sections of similar form, but 1t can be used successfully upon cross sections of extended forms, for example, rectangles. Even in these cases there is produced an entirely uniform coating, the thickness of which upon the long sides of the rectangle is not different from that upon the short sides.

In the formation of from Fig. 1 that the lpressure is applied directly on ingot or bloc A, the pressure being transmitted to the coating metal B, which metal is carried along through the die c by frictional engagement with the mandrel, as the latter is forced through the die. This feature further distinguishes the present invention from the prior processes.

In Fig. 2, instead of applying the pressure directl on the blank C (corresponding to A in Fiig. l) the pressure is applied directly to member D, corresponding to the ring B of Fig. 1, the pressure being transmitted to C.

Having described the invention, what is claimed is:

1. A process of forming compound metal bodies composed of Aa plurality of layers of metal which comprises placing the pieces of metal which are to form the compound body in a press provided with a restricted openin through which the metal is to be extruded, the adjacent ends of said pieces of metal being inclined toward said opening and simultaneously extruding said pieces of metal throu 0h said opening.

2 process of forming compound metal bodies by pressing which comprises placing blocks of metal which are to form the completed body in a press, one of said blocks having a substantially central opening in the line of the pressing force, said block being placed adjacent a die, the other block of metal having a pointed end engaging in said opening, and extruding said blocks of metal simultaneously through the opening in the die by applying prl'essure directly to the 3. A process of foryming compound metal bodies which comprises extruding a body of metal through a restricted opening `and through a body of coating metal arranged adjacent said opening only whereby the first metal carries a layer of coating metal with it through said opening, the exterior surfaces of said first metal and theinterior surfaces of the coating metal adjacent said opening being inclined toward the latter.

rods, it will be seen a Flying 4. The process of forming compound metal bodies by extrusion through a restricted aperture which comprises forcing a body of metal through an opening in a second body of metal placed between the first metal and said aperture, whereby the second body of metal will be carried through said restricted aperture by the first metal as a coating thereon, the opening in said second body of metal taperlng toward th-restricted aperture, the pressing force being applied directly to the rst metal only.

5. A process of forming compound metal bodies composed of a plurality of layers of metal which comprises placing in a press 'formed with a restricted opening, a block of metal having an opening therein larger than and tapering toward the press opening and another block of metal having a tapering end extending into the opening in the first block and extruding said blocks of metal simultaneously through said press opening.

6. A process of forming compound metal bodies composed of a plurality of layers of metal which comprises placin in a press with a restricted opening, a ring of metal having a conical interior with its small end toward said opening and a block of metal having a conical end extending into the interior of said ring and extruding said metals simultaneously through said openin 7. A process of forming compound metal bodies composed of a plurality of layers of metal which comprises placin in a press formed with a restricted opening blocks of metal having complementarily formed surfaces inclined towards such opening and a pressure directly to one of said bloc only to extrude simultaneously both blocks throurrh said opening.

8. process of formin compound metal bodies by extrusion throug a restricted opening comprising forcing a body of metal over a substantially stationary metal and then through a restricted opening whereby said first metal engages the surface of the second metal and carries a layer of the latter with it through said opening.

9. A process of forming compound metal bodies which comprises forcing a body of metal through a body of coating metal and then through a restricted opening whereby said first metal carries a layer of coating metal with it through said opening.

l0. A process of forming compound metal tubes composed of a plurality of concentric layers of metal which comprises placing in a press with a restricted opening and a mandrel passing centrally through said opening, a hollow block of metal having a tapered interior with its small end towards said opening and another hollow block of another metal having a tapered end extending into the interior of the first block and extruding body of coating Y llt) said metals simulutaneously through said opening.

11. process as in claim in which the l aperture in the first block at the point adjacent said opening' is of smaller diameter than' said opening.

12. A process as 1n taper of the conical interior of the first block is comparatively slight.

13; A process as in claim I in which pressure is applied directly to the second block only, whereby the conical end of the latter is forcibly driven into the space between the mandrel and the conical interior of the first block and then the metal of both blocks is extruded simultaneously through the press opening. In testimony whereof I hereunto aiix my signature. FRIEDRICH EI-IRMANN.

claim 10 in which the i 

